In linear devices, particularly linear power amplifiers (LPAs), there exists a problem with InterModulation (IM) signals generated from the processing of multicarrier signals. When the instantaneous peak envelope of a multicarrier signal exceeds the power rating of the LPA, excessive IM is generated. This spurious IM signal is output from the LPA into the environment. In a cellular communication environment, this means that the IM signal could adversely impact the call of a user currently operating at the same frequency as the IM signal.
One current solution to this problem is to cut back the power of each carrier in the multicarrier signal such that the IM signal generated has a signal strength below a certain maximum value (e.g. 60 dBc). However this solution penalizes the users by weakening their signals and effectively reducing the size of the cell in a cellular system.